1. Field of the Invention
The present invention relates to container closures, and, more particularly, to a pinch-to-release cap for closing a container opening.
2. Prior Art
Caustic substances and other materials in granular form are sold as household products for cleaning blockages from drains, and for other household uses. Containers for these granular materials must be provided with closures which are easy to install and remove, and which will securely retain the granular materials within their containers. Particularly where caustic substances are involved, closures must be operable with sufficient ease to assure that container contents are not inadvertently spilled or otherwise discharged during closure installation or removal.
It is desirable that closures for caustic material containers be "childproof" in the sense that at least two distinct types of movements must be performed in proper sequence to effect closure removal. Furthermore, it is desirable that such closures have relatively simple configurations which can be molded easily from relatively inexpensive plastics materials. Additionally, it is desirable that such closures be characterized by smooth lines which provide an aesthetically pleasing appearance.
Some granular caustic materials react with air and emit small quantities of gas which, if permitted to build up without relief, will cause container rupture or dislodging of the closure. Accordingly, in some instances there is a need to provide closures which will prevent pressure buildups by venting gases from within a container.
Previously proposed container closure caps have not adequately addressed the foregoing needs. Many are either undesirably difficult to operate, or they close insecurely. Many are of unduly complex configuration, have unattractive appearances, and/or are undesirably expensive to mold from plastics material. Most fail to address the need for a gas venting capability.